4 Nov 2021

Christchurch City Council is working to install a sprinkler system over the smouldering trickling filters at the fire-damaged wastewater treatment plant to help extinguish hot spots and reduce the smell.

“We are aware there are some odour issues around the plant because the plastic media housed within two trickling filters has partially melted and is giving off an acrid smell,’’ says Council Head of Three Waters and Waste Helen Beaumont.

“We hope to reduce the smell by putting a constant stream of water through the trickling filters so we are working through options for installing sprinklers over the structures.’’

Ms Beaumont says while it obvious that the roof structure and the wastewater distribution system for the trickling filters have been destroyed, it is not yet clear how much of the plastic media housed within the filters has been damaged.

It is also not yet known whether the concrete housing has been structurally compromised, although external inspections indicate there is no immediate risk of collapse.

“To undertake a full internal inspection we will need to gain access to the interior of the trickling filters and remove most, if not all, of the material inside. This is going to a challenging logistical exercise,’’ Ms Beaumont says.

“There are still hot spots deeper within the filter media – it is about six metres deep. We are assessing options for gaining access so we can do a full inspection once the material has cooled sufficiently for us to safely enter.’’

Preliminary testing of the debris from the fire indicates that none of the material contains asbestos.

Ms Beaumont says while people can still use their toilets, bathrooms and kitchens as usual, the loss of the trickling filters at the wastewater plant is impacting on the wastewater treatment process.

“We are modifying the treatment process so that we can bypass the filters, however, doing that will impact on the quality of the effluent discharge. We have assured Environment Canterbury that we will make every effort to comply with the conditions of our discharge consents and that we will liaise with their compliance monitoring officers during the recovery effort.’’

Ms Beaumont says it takes about 20 days for the wastewater that is piped into the plant to pass through the treatment process and to get discharged via the ocean outfall.  As such it will be some time before any changes in the quality of the discharge becomes evident.

“An adaptive management plan is being worked on with the objective of ensuring the best possible outcome with respect to the quality of the effluent discharge within the practical constraints of the plant,’’ Ms Beaumont says.

Health advice

Canterbury Medical Officer of Health Dr Cheryl Brunton has advised that the strong smell created by the fire at the Christchurch Wastewater Treatment Plant may persist for some time.

“Anyone experiencing any persistent health issues from the fire should contact their general practice team for advice, in the first instance,” says Dr Brunton.

Community and Public Health’s other advice is as follows:

Food safety

  • Wash home-grown fruits and vegetables before consumption.


  • If soot from the fire reached your home, you may wish to hose down your roof, outside walls, decks, paths, and driveway
  • Any large pieces of debris can be picked up using gloves. Please ensure the debris is cool and if in doubt soak in water before disposing of it in your red bin.

Internal surfaces

  • Any visible soot or dust (for example, on windowsills) can be wiped down using a damp cloth. For hard surfaces, use a mop with a mild soap or detergent.
  • Soft furnishing can be cleaned using a vacuum cleaner (preferably with a HEPA filter).


  • If you had clothes on the washing line which have been exposed to smoke and soot, put them through a rinse cycle and then wash again as usual.  Wash any other items that smell of smoke or soot.


  • Wash your pet and pet bedding if they were exposed to smoke and soot.